1. Technical Field
The present invention relates generally to cameras and, more particularly, to photo-electric interfaces employed between mechanical and electrical apparatus in cameras.
2. Background Art
In a conventional camera, both mechanical and electrical systems are employed to carry out various camera functions, such as operating the shutter, controlling the flash illumination, and advancing the film.
The mechanical systems commonly found in cameras are those that take information from the operator and direct it to the photographic process. For example, the operation of the shutter is initiated by a shutter release button switch. As another example, the presence of film is sensed when the film is inserted into the camera causing a plunger switch to be depressed.
The electrical or electronic systems commonly found in a camera generally receive information about the actions of the mechanical systems so that they may respond appropriately in implementing the photographic process. For example, when the shutter release button is pressed, it mechanically closes an electrical circuit which is usually connected to a shutter drive circuit. Upon closure of the electrical circuit, the shutter drive circuit is activated to cause the shutter to open and permit the taking of a photograph.
The interface between these mechanical and electrical camera systems is typically accomplished by some type of electro-mechanical switch requiring, in many cases, intricate mechanical assemblies. In addition, electrical contacts and conductors are necessary to transmit information from the switch to the controlling circuitry and/or electronics.
The mechanical switch assemblies have a substantial drawback in that they occupy a relatively large amount of space, which is scarce in many camera designs. Also, these assemblies must be deployed close to where the mechanical systems are situated. Further, because these assemblies require a number of moving parts, they have a relatively low reliability and high manufacturing cost.
The contacts and conductors associated with electro-mechanical switches also introduce the potential for reliability problems caused by oxidation, contamination or corrosion. Also, the electrical contacts and conductors require soldering which introduces additional potential reliability problems. Further, the assembly of these electro-mechanical components in a camera contribute significantly to the overall manufacturing cost of the camera.